Controllable fabrication of novel graphene quantum dots/fluorinated boron nitride ultralight composites for broadband and high-performance microwave absorption

The microwave absorption performance of graphene materials is severely hindered by their high dielectric constant and ultralow magnetic loss ability. Herein, for the first time, we report a simple strategy to achieve a suitable electromagnetic match by fabricating fluorinated boron nitride nanosheets supported graphene quantum dots (GQDs/F-BNNs) composites. Our results show that the reduced microwave reflection and enhanced magnetic loss are attributed to the low dielectric constant and ferromagnetism of F-BNNs, which also overcome the typically hydrophilic of GQDs to realize desirable stability in water. Then, we highlight that the absorption bandwidths and reflection loss (RLmin) are closely correlated with the size of GQDs, which is introduced by the modulated bandgap widths of GQDs concerning microwave in different frequencies. Thereinto, the optimized GQDs/F-BNNs exhibit excellent microwave absorption performance with the RLmin of −66.69 dB with a thin thickness of only 5.29 mm in 2∼18 GHz. Moreover, when the frequency reaches 19∼26 dB and 27∼40 dB, RL values are also both less than −10 dB. Our findings pave the way for GQDs and pioneer F-BNNs as lightweight and high-efficient microwave absorbing materials.